Sugar is a common carbohydrate sourced from sugar cane and sugar beet used in food because of its sweet taste. Approximately 70% of the world's sugar comes from sugar cane and about 30% comes from beets. Ordinary table sugar (sucrose) is a disaccharide made up of one molecule of glucose bound by a α-I,2-glycosidic linkage to one molecule of fructose.
The processing of sugar cane (see FIG. 12), results in the generation of a number of byproducts, most of which are considered waste products with little or no nutritional value or use in human applications. Typically they are difficult to refine further and there are often substances in the compositions that contaminate standard separating materials. However, molasses and other products of the sugar refining process, are complex mixtures of compounds, including organic molecules such as polyphenols, di/tri/polysaccharides, peptides/proteins, minerals, and organic acids.
Polyphenols (compounds with two or more phenol groups) and phenolic acids (one phenol ring—also called phenolics) are a class of phytochemicals found in a variety of sources including wine, grapes, cocoa and sugar cane and sugar beet. Polyphenols and phenolics all have a common basic chemical component, that is, a phenolic ring structure. There are at least 8000 identified polyphenols in a number of subcategories, such as anthocyanidins and catechins. Natural polyphenols can range from simple molecules such as phenolic acid to large highly polymerized compounds such as tannins. Polyphenols can exist in their free form, or as polyphenol glycosides.
Conjugated forms of polyphenols are the most common, where various sugar molecules, organic acids and lipids (fats) are linked with the phenolic ring structure. Despite having a common phenolic ring structure, differences in the conjugated chemical structure, size and other substituents account for different chemical classifications and significantly, variation in the potential biological activity, modes of action and potential influence on metabolism and resulting influence on human (or animal) health properties of the various compounds.
Role of Polyphenols in Blood Glucose Control
Polyphenols from different plant sources have been associated with a plethora of health benefits including in respect of their positive effect on the rate of carbohydrate digestibility in the body and in turn, the effect on blood glucose levels. It is on this basis that polyphenols have been used to lower the glycemic index (GI) of foods (see for example WO2005/117608 to the applicants).
The GI of a food is a measure of how quickly blood sugar levels (i.e., levels of glucose in the blood) rise after eating a particular type of food. Foods are grouped by GI value into categories: High GI>70; Medium GI between 69 and 56; and Low GI<55 (Foster Powell and others 2002; Atkinson and others 2008), whereby the lower the GI value, the slower blood sugar levels rise after having eaten the food. The GI of a food product is dependent on a range of factors, many of which are intrinsic to the food and include the levels of polyphenols. When added to foods, for example, polyphenols from green tea and soluble fibre from barley β-glucan were found to be effective in reducing the fasting plasma glucose levels of induced diabetic rats (Gao and others 2012).
The GI of foods however has been criticized for ignoring the relevance of the postprandial insulin response and the role of hyperinsulinaemia in the development of diabetes and metabolic syndrome. Continuously high insulin levels is a more significant determinant of the development of insulin-resistant conditions such as diabetes.
Physiologically, once glucose is sensed in the blood after digestion of the food and subsequent absorption from the intestine, the body (via incretins) activates the production and secretion of insulin which sends signals to the body to activate glucose uptake receptors in muscle, liver and other tissues to absorb the glucose from the blood, since glucose is the basic energy form used by the different cells and tissues in the body. Continuously high levels of glucose in the blood leads to the development of insulin-resistance, also referred to as impaired-glucose tolerance. Under such conditions, the body is unable to properly clear glucose in spite of high levels of insulin. This represents the first stage in the development of diabetes (pre-diabetes) and over time if this is not corrected, the pancreas (the organ which produces insulin) becomes overworked and unable to produce insulin. By that time, type 2 diabetes has developed.
The Insulin Index (II) is a measure used to quantify the typical insulin response to various foods. It is a measure of the insulin response in the blood over two hours after ingestion of a test food. It is often done in conjunction with GI. This measure provides additional information to the GI as some foods can still cause an insulin response despite there being no carbohydrates present. Thus, the insulinaemic index (II) (also referred to as the Insulin Index) can be used as an additional metric for classifying foods (Lee and Wolever 1998).
Not only do existing products on the market fail to consider the relevance and regulation of the insulin response, but they fail to ensure the very careful balance required to ensure that at the other end of the scale, the subject does not become hypoglycaemic. That is, glucose levels being too low. This is an important requirement for developing useful compositions for the management of conditions associated with insulin resistance, and in particular, obesity and type 2 diabetes. It is for at least this reason that the European Food Safety Authority (EFSA) requires that reductions in postprandial glucose responses to foods are not the result of an increase in insulin response, which would place undue stress on the pancreatic cells producing insulin. For example adding extra protein will cause higher insulin secretion and subsequent lower blood glucose levels.
Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.